Frontage
From AACWWiki
In military terminology, "frontage" refers to the amount of space a unit tales up along a line of battle. In AACW frontage refers to the limitation on the number of units that can be deployed on the battlefield.
Depending on the terrain and weather conditions, an army is limited in the number of troops that can be engaged. Units that move slowly will also maneuver slowly and so cannot be as readily deployed. Troops that are not engaged are held in reserve and can be sent in to relieve broken units. The game engine handles all of these details invisibly during combat resolution, but it's important to know how the system works so that you can adjust your tactics accordingly.
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Combat Units Quota
For each terrain type, there is a Combat Units Quota and a separate Support Units Quota which limits the number of combat and support elements on each side that can engage in combat during a single combat round (the quota covers all units participating in the combat, not separately computed for each division or stack). The quotas are unaffected by weather, except in the case of cities and forts, where for some reason they are somewhat reduced in clear weather.
Important: for purposes of frontage, artillery is considered a support unit, so it fills up the Support Units Quota.
Quota Costs
Each type of element will use up a set amount of the Combat Units Quota (or Support Units Quota) for each element added to the combat. This amount is affected by weather, with harsh weather generally increasing the amount of the quota that an element will use, thereby reducing the number of elements that can engage in combat.
The quota cost for each type of element is taken from the base unmodified movement cost for the specific type of element in the specific type of terrain. (e.g., cavalry are especially slow in mud, so fewer of them can be deployed).
Assigning to Combat
The game engine will randomly assign elements to be engaged in combat until the Combat Unit Cost Quota and the Support Unit Cost Quota are both filled or it runs out of elements. This process is repeated for each combat round.
The chance of a particular element being engaged is modified by:
- Whether the unit is already engaged (big increase in chance to be engaged again).
- If not already engaged, the number of hits (i.e., health) an element has (e.g., militia have lower total hits than line infantry so are less likely to be engaged).
- If routed, chance to be picked is reduced.
There is no precedence advantage for different types of elements, and no bonus if you have just one of something (like a sharpshooter), but the element’s special ability will still apply to its unit even if not engaged (first fire for sharpshooter).
If supply wagons are present, the game engine will not assign more than one supply element to combat as long as there are other types of support elements (e.g., artillery) available to fill the Support Units Quota.
Modifiers
A few specific terrain/weather combinations subtract -25% from the quotas for units in offensive posture only (so the attacker can employ fewer elements than the defender):
- Wilderness/Hills/Mtn/Swamp/Marsh in Mud or Blizzard weather.
- Fort and City in all weather.
In open terrain only (clear/prairie/desert/wood), the Units Quotas are modified by leader (rank)*(offensive/defensive rating) depending whether in offensive or defensive posture:
- Combat Units Quota: (+25 points)*(rank)*(off/def rating)
- Support Units Quota: (+10 points)*(rank)*(off/def rating)
The leader bonus comes from the senior general in command. This bonus can be HUGE. A mediocre 1* general with 1 off/def would get a +25 bonus, while a 2* general with a 3 off/def would get a +150 bonus (+60 for support units), so he could bring about 60% more infantry elements to the fight, and twice as much artillery!
Other Notes
Elements from the same unit will all fire against the same enemy unit. If they have overwhelming firepower and destroy the enemy unit outright, the excess firepower for the round is “wasted” and not redirected at another enemy unit. With multiple divisions engaged, you may only see casualties in one because the enemy’s fire was all directed at the same unit.
Corps support artillery (unassigned to divisions) will fire on the healthiest (i.e., strongest) enemy unit. This may not be the same unit that it is directly opposed against.
Notes on Terrain/Weather/Unit Type Combinations
There are literally hundreds of different combinations of terrain/weather/unit type. Here are some general comments:
- Cavalry have a big frontage advantage over infantry in clear/city/fort terrain + clear weather, but not in any other conditions, and they especially don’t like mud.
- Forts and cities have the lowest quotas (Forts are somewhat better) and they also impose a -25% quota penalty on the attacker.
- Light infantry have the lowest all around frontage cost, especially in rough terrain and harsh weather.
Strategy Notes - General
- Don’t underestimate the importance of the leader bonus for frontage. If you have a stack with a very strong leader, try to engage the enemy in open terrain, and feel free to pack in extra artillery, because the frontage bonus means you can put more of them onto the battlefield in open terrain. On the flip side, if you have a weak leader, stick to rough terrain if possible to minimize your opponent’s leadership advantage.
- Cavalry have 2:1 frontage advantage over infantry in clear terrain, but it doesn't seem very useful -- cavalry actions are usually small, and the frontage quota in clear terrain is so high that you could never fill it with cavalry unless you find a way to make 5 full cavalry divisions and stack them together.
- For cavalry raider divisions, keep in mind that horse artillery are support units, so they don’t detract from the number of cavalry elements you can field. So even in rough terrain, some horse artillery will add a lot to your firepower. Horse artillery…don’t leave home without it.
- In general, a smaller force should always try defend to against a larger force in rough terrain, and a larger force should use caution advancing through the mountains.
- Remember that the frontage limitations are only per round. Battles occur in multiple rounds, and in each round different units can cycle in and out. So, even if your force is too large for the allowed unit quota, it’s still an advantage to have a larger force because your fresh units can relieve your damaged ones. Ultimately a much weaker force will succumb.
Strategy Notes - Artillery
- Because Artillery fills up the Support Units Quota, they won’t compete with infantry for engagement slots. But, they will compete with other support units. This shouldn’t be a big deal, since supply wagons will only put in one element, but if you also have engineers, signal, and recon units, it could all add up to a reduced number of artillery elements on the field.
- The maximum number of artillery elements in combat is 15 in open terrain (or city/fort) and clear weather. But in any other kind of weather or terrain, artillery is severely reduced (from just 2 elements in mtn/blizzard to 10 in wood/clear, but averaging about 6 across all terrain/weather combinations). This number can be reduced by supply or other support units taking up Support Units Quota points, or increased by the leader bonus.
- Most importantly, leader ability can drastically increase the number of artillery units you can use in open terrain (clear/prairie/desert/wood). An average leader will raise the maximum in open terrain and clear weather to 17. A strong 2* leader can raise it to 30, and a super leader to 45 or more. Basically, a good leader can double your artillery frontage, and a great one can triple it (but only in open terrain).
- Frontage rules put a practical limit on how many artillery elements to put into a stack (or division). But how many is ideal? It depends on the size of the stack – whether it’s a solo division or smaller independent force, or a large multi-division stack like a big corps. With any more than 6 artillery in a stack, you are likely to have some idle artillery units that will not engage. On the other hand, in a big stack, if you have 15 artillery you know you are always bringing maximum firepower to bear.
- My recommendations: 4 artillery per division in a large corps (less if you assign artillery at the corps level). Up to 6 or 7 in an independent division. More in a static defensive position in open terrain, fort, or city. If you have a strong stack commander, increase the amount of artillery and try to stick to clear terrain, but don’t overdo it – in anything but clear terrain your excess artillery is dead weight. Having too much artillery is not a bad thing, except for the cost of producing it and the CP cost of having it in your stack.
- Consider using massed artillery in an Army HQ stack, along with an extra general with the artillerist ability (like Huger for the CSA). Imagine Lee with a super army HQ stack packed with 20+ artillery, in clear terrain, marching to the sound of the guns to support Jackson’s corps. All 20 of those guns will target the largest enemy unit, possibly obliterating it in a singe round! Just don’t let the artillery army HQ stack get caught on its own – better to keep it in the same region as a subordinate corps for protection, since the larger corps stack would be targeted by the enemy in combat. This strategy sounds viable in the game, and it also seems historically appropriate.
- Forts and cities have the same high frontage allowance as clear terrain, but no leader bonus. As it is, the frontage allowance is more than enough to allow you to pack large quantities of artillery into your forts and cities.
References
AGEod AACW Forum post [1] Includes downloadable spreadsheet with frontage data for each type of unit/terrain/weather.
